Dan,
24" sounds good. My 10 gallon tanks are a bit smaller. Sounds like you might have a 15 or something.
Maybe he just doesn't want to feel completely exposed in the light. Have you tried using hides on both sides of the tank? You can also create a basking perch on that vine by covering it with a fake plant. He might feel more inclined to bask if he felt more secure.
Also, you could put a heat pad on the back or the side of your tank, near the top and, and that would give you a horizontal and vertical heat gradient, which seems to help in keeping semi-arboreal species.
I don't keep Carpets (yet!), but from what I've read, they like it in the mid 80's with a basking spot of around 90.
BTW, I am not knocking on how you keep your snake, cause I really don't know if you do all these things or not. I am just trying to throw out some suggestions based on things I've read, not personal experience.
Fluffy definitely looks healthy and beautiful. If he has those colors at this age, he is gonna be a SCREAMER of an adult!! I am jealous! Good luck and I hope this helped some.
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Diego & Tiffany's Zoo
SNAKES
4.4 Corn Snakes (Different morphs)
1.0.0 Boa Constrictor
0.1.0 Dumeril's Boa
0.1.0 Tangerine Honduran Milksnake
1.0.0 Honduran Milksnake
0.1.0 Mexican Black Kingsnake
1.1.0 Ball Pythons
0.0.1 Ribbon Snake
0.0.2 Rosy Boas (Mid Baja & Baja)
0.1.0 Pueblan Milksnake
1.2.0 Kenyan Sand Boas
1.0.0 Western Hognose
0.1.0 Solomon Island Boa
1.1.0 Gray Banded Kingsnakes (River Road)
0.0.1 Desert Phase Kingsnake
LIZARDS
1.0.0 Frilled Dragon
3.1.0 Bearded Dragons (2 Normal, 1 RedXGold, 1 Citrus)
0.1.0 Eastern Collared Lizard
0.1.0 Merauke Blue Tongue Skink
1.0.0 Turquoise Sunburst Veiled Chameleon
0.0.3 Leopard Geckos
1.1.0 Yellow Niger Uromastyx